1. Field of the Invention
This invention relates to an electronic typewriter which is capable of temporarily storing data from a keyboard in a print buffer and of printing the data on a printing paper in accordance with the contents of the print buffer, with shifting of a carriage having a print head thereon.
2. Description of the Prior Art
An electronic typewriter having a print buffer usually sequentially executes printing, shifting of carriage and paper feed, in accordance with data sequentially stored in a print buffer. Thus, for example, when a tab key, for shifting the carriage with print head up to a preset tab position is operated after operating a carriage return key, the carriage shifts first up to a left margin position in order to execute the carriage return operation and then shifts up to the preset tab position. The carriage shifting speed becomes zero when the carriage return operation has been completed and then becomes zero again when the carriage moves forward up to the preset tab position.
When the space key is depressed twice after the tab key is depressed, the carriage shifts at first up to the preset tab position in order to execute the tab operation and stops. Then, the carriage shifts for one space and stops again. Then, the carriage shifts again for one space.
As indicated in this example, the carriage goes backward and forward in the same area even when no printing operation is carried out or when the carriage stops between the tab position and the space data; or between the space data even when the head shift data for no printing operation is continuously inputted. For this reason, the carriage executes meaningless increase or decrease of shifting speed, or shifts in a meaningless range. Thus, the head shift data processing requires a longer time and power consumption is increased. Particularly, large power consumption becomes a problem when the typewriter or like is driven by a battery, since such large power consumption tends to decrease the operating life of the battery.